High pressure rotary engine, especially for hydraulic transmissions



Jan. 16, 1934. E. sTuRM 1,943,637

HIGH PRESSURE ROTARY ENGINE, ESPECIALLY FOR HYDRAULIC TRNSMISSIONS.

Filed Dec` 18, 1929 Patented Jan. 16, 1934 UNITED STATES HIGH PRESSURE ROTARY ENGINE, ESPE- CIALLY v FOR HYDRAULIC TRANSMIS- SIONS Erwin Sturm, Stuttgart-Botnang, Germany Application December 18, 1929, Serial-No. 415,000. and in Germany May 18, 1928 1 Claim.

For hydraulic transmissions engines with reciprocating pistons or rotary engines (enclosed engines) with rotary piston drum have hitherto been employed as driving or driven elements.

The piston engines permit of the application of higher driving medium pressures and of higher running speeds, giving however smaller eciencies per revolution and being expensive to manufacture. Besides this, their rotating mass is great, and only a small portion of the driving medium pressure is converted into turning force.

The rotary engines on the other hand present the advantage of larger quantities delivered per revolution, of smaller rotating masses, and of a tangential action of the driving medium pressure. They are moreover cheaper to produce. Most of the known rotary engines however are only suitable for limited rotating speeds, and all allow of only low pressures because with higher pressures the clearance losses become too great.

This invention has for its object to construct the rotary engines so that, at high delivering efficiency, they allow also the application of high numbers of revolution and oi' high pressures, remaining however always simple and cheap to manufacture. l

This is attained according to the invention by arranging that the sliding pistons, mounted in the piston arm, bear with surface packing against a drum casing rotatably mounted eccentrically to the piston'drum and rotate therewith. By this arrangement the friction of the liquid and the mechanical friction between pistons and casing is considerably reduced as, even at high rotating speeds, only the very small relative speed between the piston and casing comes into question as friction speed. This low relative speed also enables movable running elements to be tted into the outer ends of the sliding pistons, which running elements adapt themselves with a surface on the casing wall and thus produce a very effective packing between the pressureand suction-side, without excessive friction or compression (such as occurs with stationary drum casing) being caused thereby.

'Ihe slight relative speed also allows the sliding pistons to be guided by guides which are mounted in guide grooves rotating with the end walls of the drum casing. The guide grooves are situated entirely or partly in the working space of the engine so that theguides likewise situated therein are subjected to the pressure of the driving and running medium. To enable this pressure to press the guides outwards against the drum casing the outer guide surface o1' each guide is greater than the inner guide surface. Thus a power component outwardly acting on the side surfaces of the guides, is produced, which component presses these guides and therewith the sliding pistons with the running elements against the inner surface of the drum casing. This pressure increases as the difference between the outer and'inner guide surface of the guides becomes greater. It is therefore possible to vary the pressing on pressure as desired. This ccn 65 struction of the guides presents the advantage that the guide grooves in the piston drum behind the sliding pistons need not be subjected to greater pressure than hitherto customary. Consequently the casing may be made of smaller diameter.

Y Several embodiments of the invention are illustrated by way of example in the accompanying drawing in which:

Fig. 1 shows a longitudinal section through a 75 rotary engine.

Fig. 2 is a cross section on line 2-2 of Fig. 1.

Fig. 3 shows a portion oi' Fig. 2 on a largerl scale.

Fig. 4 is a side elevation of the piston.

Fig. 5 shows another form of construction of the piston slide with working part in end elevation.

Fig. 6 is a side elevation of Fig. 5.

A piston drum 4 is journaled by means of bear- 85 ings 3 in the covers 1 o f a stationary outer casing 2. The piston drum i4 runs in a casing 5, formed by a ring 5 and by covers 6 arranged on each side of the ring. This casing, hereinafter referred to as the drum casing, is journaled in bearings l in the covers l.

The piston drum 4 has a number of radial slots 8, in which sliding pistons 9 are slidably arranged. Pins 10 project one on each side from each of said pistons and engage in guides 11 situated in an- 95 nular grooves 12 in the covers 6. A positive guiding of the sliding pistons is thereby obtained, ensuring the bearing of the piston ends on the drum casing bore.

These 4annular grooves are preferably arranged 100 as near as possible to the bore of the drum casing 5. In the example illustrated they are displaced so far towards the outer side, that the bore of the drum casing 5 forms itself the outer surface of the guide grooves.

In order to obtain a surface packing of the sliding pistons 9 in the bore of the drum casing 5, running elements 13 are loosely inserted in the outer ends of the pistons 9 and bear 'against the drum casing 5. In order to obtain that the 110 running elements 13 press against the path of travel, the guide elements 11 are of such shape, that the outer guiding face 1l is larger than their inner guiding face 1i. As the annular grooves l2 in which the guides 1l move cornmunicate laterally with the working space, the driving medium pressure also acts on the guides. Owing to the two guide elements 11' and 11" of different sizes, a power component acting on the side surfaces of the guides is produced, which component presses the guides 1l and therewith the sliding pistons 9 with the running elements 13 against the inner surface of the drum casing 5. The greater the difference between the outer and inner guide surfaces of the guides 11 is, the stronger will be the pressure with which the running elements 13 are pressed against the inner wall of the drum casing. which pressure increases with the increasing pressure medium pressure. By making the guide surfaces 1l and 11" sulciently large it is therefore easily possible to maintain the pressing on pressure within the desired and necessary limits.

The running elements 13 may be in the shape of cylinders flattened parallel to the longitudinal axis (Figs. 3 and 6) or in the shape of T-shaped shoes 13 (Fig. 4).

In order to obtain a permanent bearing of the pistons 9 in the guides l1, the guide pins 10 may be fitted with pressed on bushes 15 (Figs. 5 and 6) The piston drum 4 rotates around a centrally situated, cylindrically turned hollow body 16, which is provided with a passage 17 for the feed of the driving mediumand with a passage 18 for discharge of the driving medium. These passages communicate with the working space in known manner by means of passages 19 arranged radially in the drum 4. The drive of the piston drum 4 is affected by an axle end 20.

A rotary piston engine, comprising in combination a stationary outer casing, a rotary casing freely rotatable in said outer casing, a drum rotatable in said rotary casing forming therewith the working space of the engine, said rotary casing composed of a ring and two covers one on each side of said ring, said covers having annular grooves on their inner surface communicating with said working space, pistons shiftahly mounted in said drum, running elements pivotably mounted one on the outer end of each of said pistons, guides in the annular grooves of said covers hngedly connected on both sides of said pistons adjacent their outer ends, the outer guide surfaces .of said guides in said annular grooves being larger than their inner guide surfaces to allow said pistons to be pressed outwards by the fluid pressure and press said running elements tightly against said freely'rotatable casing.

ERWIN STURM. 

